#include<stdio.h>
int factorial(int n);
int main(void)
{
	int n;
	
	scanf("%d", &n);
	printf("%d\n", factorial(n));
	
	return 0;
}

int factorial(int n)
{
	int i, fact = 1;
	
	for(i = 1; i<=n; i++){
		fact=fact*i;
	}
	
	return fact;
}